The present invention relates to the manufacture of fibriform material comprising a smoke-modifying agent.
GB 2 070 409 discloses a filament comprising smoking-modifying agents. The filament may be formed of or obtained from a fibrous material, such as tobacco, paper, cotton or man-made textile fibres, which material readily carries or can be readily impregnated with smoke-modifying agents. A possible disadvantage of the invention the subject GB 2 070 409 is that the smoke-modifying agents, if volatile, as is menthol for instance, can readily migrate from the filament, resulting in losses of the agent(s). The migration of significant amounts of the smoke-modifying agents from the region of application is highly undesirable and thus for example methods of encapsulation of flavourants have been devised to prevent such migration. Considerable work has been undertaken in respect of the encapsulation of flavourants in beads or microcapsules. However, problems may exist in maintaining such beads or microcapsules in cigarette tobacco rods.
U.S. Pat. No. 5,144,966 discloses a flavourant-release additive in the form of a filament for incorporation in the combustible filler of cigarette products and a method of production of such a filament. The filament disclosed in U.S. Pat. No. 5,144,966 comprises a core matrix and a co-extensive sheath coating, wherein the core matrix comprises a mixture of flavourant compound and a polysaccharide binder, and the sheath coating comprises a non-porous calcium alginate film. Such filaments are produced by a process which comprises 1) extruding an aqueous mixture of flavourant compound and a polysaccharide binder through an inner nozzle to form a gelled core fibre, 2) simultaneously co-extruding an aqueous solution of water-soluble alginate salt through an outer nozzle, coaxial of the inner nozzle, to apply a co-extensive sheath coating on the core fibre, and 3) contacting the thus formed filament with an aqueous calcium compound solution to convert sodium alginate to insoluble calcium alginate in the filament sheath coating, thus to encapsulate the flavourant. This co-extrusion method for forming a type of encapsulated filament is cumbersome when producing large quantities of filaments, which of course would be required if such filaments were to be incorporated into cigarettes at commercial manufacturing speeds.
It is an object of the present invention to provide an improved and commercially practical process for the manufacture of a fibriform material comprising a smoke-modifying agent(s).
The present invention provides a process for the manufacture of a homogeneous fibriform element comprising a smoke-modifying agent, wherein a mixture comprising a solution of a polysaccharide and a smoke-modifying agent is fed through nozzle means, and a jet of said mixture issuing from said nozzle means is brought into contact with a solution containing multivalent cations thus to effect solidification of said mixture.
The element manufactured by the inventive process is homogeneous in the sense that the polysaccharide and the smoke-modifying agent form together a matrix of constant constitution throughout the element and the term xe2x80x9chomogeneousxe2x80x9d is to be interpreted accordingly.
As will be appreciated by those skilled in the art, the process of solidification, i.e. the production of the aforesaid matrix, proceeds by way of a chemical reaction between cations of the solution containing multivalent cations and cations of the polysaccharide.
The non-solid mixture may take the form of, for example, a solution, a dispersion or an emulsion.
Advantageously, the mixture is heated to provide an elevated temperature of the mixture of, for example, 45xc2x0 C. and is fed at an elevated temperature through the nozzle means. Suitably, whilst at an elevated temperature, the mixture is stirred continuously.
Preferably, the jet of the mixture issuing from the nozzle means is fed into a body of the solution containing multivalent cations. More preferably the jet of the mixture issuing from the nozzle means is fed into a stream of the solution. In the latter case, the stream of the solution containing multivalent cations suitably flows in a direction substantially parallel to the direction in which the mixture is fed through and issues from the nozzle means. Advantageously, the stream of the solution containing multivalent cations flows within conduit means. When conduit means are present the nozzle means and conduit means may suitably form an integral unit. Suitably, the mixture issuing from the nozzle means is carried by the solution containing multivalent cations through a portion, at least, of the conduit means. The length of the conduit means through which the mixture is carried is preferably of a length such that solidification of the mixture is complete or substantially complete upon issuance of the mixture from said conduit means at the downstream end thereof. As a person skilled in the art will readily appreciate, the flow rate of the mixture issuing from the nozzle means will affect the residency time of the mixture within the conduit means. It is conceivable too that this residency time may be affected by the flow rate of the cation containing solution.
Alternatively, the solution containing multivalent cations may be sprayed onto the jet of the mixture issuing from the nozzle means.
Suitably, the mixture is forced to and through the nozzle means under the action of a positive displacement pump, for example a progressing cavity pump as manufactured by Robbins and Myers under Model No. B4015. Alternatively, the mixture may be forced to and through the nozzle means under the action of pressurised air. Much by preference the mixture should exit the nozzle means at a substantially constant flow rate. The mixture may be continuously agitated in storage means before being fed to the nozzle means
According to a second aspect thereof, the present invention provides a process for the manufacture of a fibriform element comprising a smoke-modifying agent, wherein a thread is passed through a mixture comprising a solution of a polysaccharide and a smoke-modifying agent whereby said thread is coated with said mixture, the coated thread being brought into contact with a solution containing multivalent cations thus to effect solidification of said mixture on said thread.
Advantageously, the thread is comprised of a fibrous material, for example, tobacco, paper, cotton or a man-made textile.
As will be readily apparent to those skilled in the art, a fibriform element the product of a process according to the second aspect of the present invention is of homogeneous constitution in the sense of the above definition of xe2x80x9chomogeneousxe2x80x9d, excepting, of course, for the presence in the element of the thread.
In carrying out the process according to either of the above defined aspects of the present invention, as an alternative or in addition to bringing the mixture comprising a solution of a polysaccharide and a smoke-modifying agent into contact with a solution containing multivalent cations, the mixture can be brought into contact with an acidic solution, acetic acid for instance, thus to effect solidification of said mixture.
Suitably, the so-formed solidified fibriform element (formed according to either aspect of the invention) is wound onto a rotating drum. Preferably, the drum, at least at the peripheral region thereof, is comprised of plastics material. Preferably, the fibriform element is wound onto the drum, at least initially, in a single layer. A traverse unit may be used to pitch the fibriform element across the drum as the element is wound onto the drum. If it is deemed necessary, the drum, or a lowermost portion thereof, may be positioned in a bath containing the cation solution, so that as the drum, with the element wound thereupon, rotates, a lowermost portion of each turn of the element is immersed in the cation solution.
Following solidification of the fibriform element, the element may be washed, in for example water.
If there is a requirement to dry the so-formed fibriform element, various methods are available to persons skilled in the art for drying the element. For example, the element wound on the drum may be placed, along with the drum, in an oven at a pre-set temperature for a pre-determined period of time or alternatively air drying means may be used to dry the element on the drum. As another alternative, the element, before being wound onto the drum, may be passed through an annular air knife or a drying tunnel, or multiple combinations thereof. As a person skilled in the art would readily appreciate, combinations of these various methods may also be used.
Conveniently, the fibriform element in a dry, non-adhesive condition, is removed from the above mentioned drum and wound onto a lesser diameter spool for storage, the spool being of an appropriate diameter such that excessive bending of the element is avoided. Alternatively, the element can be cut into lengths, of about 30 cm for example, and stored for subsequent use. According to another alternative, the solidified fibriform element may be stored on the rotatable drum.
Elements manufactured by use of the present invention are preferably not breakable merely by being bent or drawn on longitudinally. Thus, if deemed necessary, plasticisers, glycerol and/or propylene glycol for instance, can be added to the initial mixture in order to increase the flexibility and/or tensile strength of the elements.
The initial mixture may further comprise an emulsifier if such an emulsifier is considered to be a requirement. The emulsifier may be, for example, a modified polysaccharide such as modified starch.
The homogeneous element is such that at least one smoke-modifying agent is encapsulated, in the sense of being held in the element against escape therefrom by, for example, volatilisation at ambient temperatures.
The polysaccharide solution is preferably an aqueous solution. The polysaccharide may suitably be an acid polysaccharide in the form of an alkali metal salt, for example an alginate, particularly sodium alginate. Other suitable polysaccharides which may be contemplated include pectins, gellan gum, carrageenan, agar, gum arabic, xanthan gum and guar gum.
The solution containing multivalent cations may be for example, an aqueous or alcoholic solution. The multivalent cations are ions of the group consisting of calcium, strontium, barium, iron, silver, aluminium, manganese, vanadium, copper and zinc, particularly calcium ions. For instance, a suitable aqueous solution containing multivalent cations is aqueous calcium chloride.
The present invention further provides a fibriform element as manufactured by a process in accordance with the present of invention.
Much by preference, the fibriform element is of a constant cross-sectional shape and size along the length thereof. Suitably, the element is of circular cross-section, in which case the diameter thereof will generally not be more than about 3 mm, preferably not exceeding about 1 mm.
The present invention further provides a smoking article comprising a smoking material rod, within which rod there extends, generally longitudinally of the rod, a fibriform element as manufactured by a process in accordance with the present invention.
Preferably, the fibriform element extends co-extensively of the smoking material rod. More than one fibriform element may extend, within the smoking rod, generally longitudinally thereof, in which case, preferably each of the elements extends within an axial zone of the rod. Advantageously, if a single only element extends within the smoking material rod, the element extends at least substantially coaxially of the rod. An advantage existing as a consequence of the element(s) extending within an axial zone of the smoking material rod is that when a smoking article comprising the smoking material rod is smoked, losses of smoke-modifying agent to sidestream smoke are minimised and thus the transfer efficiency of the smoke-modifying agent to the mainstream smoke is improved.
Suitable smoke-modifying agents may comprise, for example, tobacco dust or flavourant(s), menthol and/or furaneol, for example. In the former case, the tobacco dust may be impregnated with a flavourant.